Due to the development of equipment for wireless transport of data, for example e-mail, many network operators are establishing such services for their customers. Future fields of use may be to acquire video sequences from an on-going sports event, for example a game of football. When a goal is scored one may watch the event on, by way of example, a cell phone monitor.
Previously, so-called circuit coupling has been used for transmission of data. Data is then sent via a line, and the operator charges the user for the time the line is open. Then data is only sent sporadically, and the user pays for the capacity that is reserved for him.
When using GPRS (Global Packet Radio Service), data is sent in packages and the operator then has the possibility to charge the user for the amount of data that is sent. Using this service, the line is either shared with other users, or only open when the packages are transmitted.
Previous GPRS systems are called 2.5 G (second and a half generation) and use GSM (Global System for Mobile communication) as a radio system. Now the operators are going to introduce 3 G (third generation) where GPRS uses UMTS (Universal Mobile Telecommunications System) as a radio system. UMTS is faster then the older GSM, and has the support of many major telecommunications operators and manufacturers because it represents a unique opportunity to create a mass market for highly personalised and user-friendly mobile access to tomorrow's information society. UMTS will deliver pictures, graphics, video communications and other wideband information as well as voice and data, directly to people who can be on the move. UMTS builds on the capability of today's mobile technologies (like digital cellular and cordless) by providing increased capacity, data capability and a far greater range of services using an innovative radio access scheme and an enhanced, evolving core network.
However, the introduction of UMTS is expensive for the operators as licenses have become very expensive for many 3 G operators. The equipment is also quite expensive. One way to decrease the cost of the UMTS introduction is for two or more 3 G operators to establish a shared 3 G radio network. Some network elements are located in the home network of a respective operator. Example of network elements in the home network are GGSN (Gateway GPRS Support Node) and HLR (Home Location Register). The GGSN is a gateway node that terminates specific protocols, and the HLR is a large data base containing information about all subscribers. The shared network must be able to pass outgoing packet sessions via the correct home network.
A network may be shared by two or more operators. For illustrative reasons we suppose that the shared network is shared by two operators and call them operator A and B. If two mobile terminals, MT1 and MT2, which are subscribed to operator A and operator B, respectively, are going to pass outgoing data packet sessions via the shared network, an SGSN (Switching GPRS Support Node), a kind of switch, in said shared network is able to pass said outgoing packet sessions via the correct home network of the operators A and B.
If a visiting mobile terminal MT3, which is subscribed to an operator X, is going to pass outgoing data packet sessions via the shared network belonging to operators A and B the shared network is able to determine that MT3 is a visiting mobile terminal, and that it may use the shared network (operator X has an agreement with either operator A or operator B, or both). The shared network is, however, not able to determine via which home network of the operators A and B the data packages are to be passed. The result is that it is not possible to predict towards which GGSN the visiting MT3 will establish a so-called PDP context (Packet Data Protocol), i.e. a connection for GPRS.
If two mobile terminals MT3 and MT4 are subscribed to operators X and Y, respectively, and are going to pass data packages via a shared network belonging to operators A and B, the SGSN in said shared network may only state that MT3 and MT4 are visiting mobile terminals, and if they are allowed to use the shared network, nothing else.
It would be of interest to route the visiting mobile terminals in a shared network, subscribed to different operators, that not are the ones that own the shared network, to predetermined home networks of the operators that own the shared network depending on which operators the visiting mobile terminals are subscribed to. There is no way for the current available technology to admit the shared network to identify to which operator a visiting mobile terminal is subscribed.